I. Field of the Invention
This invention relates to a novel cancer-related human galactosyltransferase. Since the cancer-related human galactosyltransferase of the present invention is mainly found in cancer patients, the galactosyltransferase of the present invention may be employed as a cancer marker. Thus, a monoclonal antibody specific to the galactosyltransferase of the present invention may be used as a diagnostic of cancer, and the galactosyltransferase of the present invention can be used as a reagent for preparing the monoclonal antibody.
Further, the present invention relates to a monoclonal antibody which is specific to a cancer-related human galactosyltransferase. The present invention also relates to a hybridoma producing the monoclonal antibody and to a method of measuring the cancer-related human galactosyltransferase using the monoclonal antibody of the present invention. The monoclonal antibody of the present invention may be used as a diagnostic reagent of cancer.
II. Description of the Related Art
Galactosyltransferase (hereinafter also referred to as "GT" for short) is an enzyme which catalyzes the transfer of galactose from uridine-5'-phosphogalactose (UDP-galactose) to non-reducing terminals of oligosaccharides of various glycoproteins or monosaccharides, which occurs in almost all the tissues in the body. Abnormal activity of GT has been recognized in various malignant tumors and the possibility of employing the GT as a cancer marker has been investigated. As a result, it was discovered that the level of GT-II which is an isozyme of GT in serum has close relationship with the existence of a cancer. The GT-II is defined as the GT enzyme activity in a band obtained in Native-PAGE (polyacrylamide gel electrophoresis), which has slower mobility than the GT-I which mainly exists in normal humans, as described in Biochem. Biophys. Res. Common, 65(2), pp.545-551, 1975. Further, MAb3872 which is a monoclonal antibody corresponding to the GT-II has been reported (Cancer Research, 48, pp.5325-5334, 1988). However, the nature of the GT-II has not yet been characterized.